Evaluation of a fluorodensitometric method for analysis of ergosterol as afungal marker in compound feeds

Ergosterol is the principal sterol of fungi and plays an essential role as a component of the cell membrane and other cell constituents. This molecule is considered a good marker of fungal contamination in foods and feeds. Th is paper reports a rapid and sensitive method to test ergosterol content in compound feeds based on fluorodensitometry after thin-layer chromatography (TLC) separation. This method involves a thermal treatment of TLC plates t hat leads to the formation of a highly fluorescent ergosterol derivative. S uch a dosage allows egosterol testing in any naturally contaminated samples (limit of detection: 1 ppm of ergosterol) and gives results in close agree ment with high-pressure liquid chromatography determination. Moreover, valu es obtained on mixed feeds for animals at different steps of fungal contami nation are linked to quantitative development of storage fungi, evaluated b y mycological technique, reinforcing the interest of a rapid method for mea suring this fungal marker.